The present invention is directed generally to stereoscopic devices and specifically to a stereoscopic telescope.
Stereoscopic optical devices are becoming increasingly important not only to consumers but also to professionals in a broad variety of applications. By way of example, in still photography and video stereoscopic images are generally considered as a highly desirable alternative to two-dimensional images.
In designing a stereoscopic optical device, such as a still camera and/or video recorder, there are a number of important considerations. First, the device should produce a stereoscopic image of high quality. Second, the device should permit the user to visually preview the image(s) being acquired by the device. This feature would help the operator to aim the device for more accurate image acquisition. Finally, the device should be capable of acquiring images of objects having a greater diameter than the lens diameter of the device. Otherwise optical losses would detrimentally impact image quality.
These and other design considerations are addressed by the present invention. Generally, the optical device of the present invention projects one portion of the image radiation onto one or more imaging devices and another portion of the image radiation onto one or more oculars for two- or three-dimensional viewing by a user. xe2x80x9cImage radiationxe2x80x9d refers to radiation that has contacted the object and therefore contains image information describing the object. Image radiation is typically light that has been reflected by the object. In this manner, the user is able to preview the object being imaged by the imaging device (i.e., during image acquisition) and adjust the orientation of the optical device as desired for a more desirable image. The optical device can be in any number of configurations, such as a single lens reflex camera, a single lens telescope, and a single lens telephoto video camera.
In one embodiment, the optical device of the present invention includes:
(a) one or more first lenses to project radiation along a first optical path;
(b) at least a first dividing surface for dividing the projected radiation into first and second radiation portions;
(c) at least a second dividing surface for dividing the first radiation portion into first and second radiation segments;
(d) one or more second lenses for focusing the first radiation segment on an imaging surface, the imaging surface being a part of an image acquisition device; and
(e) one or more third lenses for focusing the second radiation segment for viewing by a user. Depending on the configuration of the device, the user can see a two- or three-dimensional image of the object.
The first lens(es) can be any suitable lens for gathering image radiation and projecting the gathered radiation along a selected optical path. The first lens(es) can thus be any type or focal length lens. For example, the first lens(es)can be reflector telescope lens(es), refractor telescope lens(es), Schmidt-Cassegrain telescope lens(es), telescopic periscope lens(es), telephoto lens(es), zoom telephoto lens(es), long focal length surveillance lens(es), and other optical classes of telescopic lenses.
The first dividing surface is typically one or more of a reflective surface, a refractive surface, an encoder that causes each of the first and second radiation portions to have a different characteristic (e.g., intensity, phase, wavelength distribution, polarization orientation, color, and/or frequency. In one configuration, the first optical path is transverse to the second and third optical paths and the second and third optical paths are in differing locations. Specific examples of dividing surfaces used in this configuration include a mirror (e.g., a partially silvered mirror, a pair of transversely oriented mirrors, etc.), a prism, and/or a beam splitter. In one configuration, the first optical path is transverse to only one of the second and third optical paths. Specific examples of dividing devices used in this configuration include at least two plane polarizers having differing polarization orientations, at least two circular polarizers having differing handedness, at least two color filters passing differing wavelength bands, at least two (mechanically or opti-electrical) shutters passing radiation at differing intervals, and a retarder covering only a portion of the first optical path. A pair of shutters in some applications is not preferred because the switching speed may be too low to produce a high quality stereoscopic image, particularly when the object being imaged is moving or changing shape.
The second dividing surface is typically a reflective or refractive surface that directs the first and second portions of the first radiation along selected optical paths. In one configuration, the second dividing surface is one or more of a beam splitter, a prism, front silvered mirrors, and/or rear silvered mirrors.
The second and/or third lenses can be any suitable lens or lens system that can project and/or focus the respective portion of the image radiation on the desired surface (which can be the imaging surface or the user""s eye). In one configuration, the second and/or third lenses includes a rear-focus conversion lens. In one configuration, the third lenses include an ocular or ocular lens system for focusing the third radiation portion on the user""s eye.
The relative positions of certain optical elements can be adjusted to accommodate the user. For example, in one configuration the distance between the rear-focus conversion lens and ocular is adjustable by the user. In one configuration, the second dividing surface, second lens(es), and third lens(es) are movably disposed in the optical device for interocular adjustment (where the optical device has two or more oculars).
The optical device can be any device and/or medium that can acquire or capture an image. For example, the image acquisition device is typically an image orthicon tube, a CCD array, a CMOS array, any other method of recording an image electronically (whether analog or digital), and/or any method of recording photographically such as (cinema or camera) negative or positive film. In one configuration, a plurality of image acquisition devices (typically two) are connected to the optical device to create a plurality of images of the object. The various images can be viewed by traditional techniques to perceive a three-dimensional image. By presenting the two images in sequence, a video or film stream can be created.
The optical device can include other lenses or lens systems and/or other optical elements. In one configuration, the optical device includes a positive and/or negative meniscus positioned between the first lens and the first dividing surface. In one configuration, the optical device includes:
(a) a third dividing surface for dividing the second radiation portion into third and fourth radiation segments, the third and fourth radiation segments following sixth and seventh optical paths, respectively, the sixth and seventh optical paths being transversely oriented;
(b) one or more fourth lenses for focusing the third radiation segment on a second imaging surface, the second imaging surface being a part of a second image acquisition device; and
(c) one or more fifth lenses for focusing the fourth radiation segment for viewing by the user. In this configuration, the use of two oculars, each passing differing portions of the image radiation, permits the user to view a three-dimensional image.
The second dividing surface can be configured to activate or deactivate the image acquisition process. For example, the second dividing surface in a first operational mode forms the first and second radiation segments and in a second operational mode does not form the first and second radiation segments. This can be realized by moving the second dividing surface into and out of the optical path of the image radiation.
In another embodiment of the present invention, the optical device includes:
(a) one or more first lenses to project radiation along a first optical path;
(b) at least a first encoder (typically positioned at or near an aperture stop or conjugate thereof) for encoding the projected radiation into first and second radiation portions, the first and second radiation portions having a different characteristic;
(c) at least a first directing surface for directing the first and second radiation portions along second and third optical paths, respectively, the second optical path being transverse to the third optical path;
(d) one or more second lenses for focusing the first radiation portion on an imaging surface, the imaging surface being a part of an image acquisition device; and
(e) one or more third lenses for focusing the second radiation portion for viewing by a user.
In another embodiment of the present invention, a method for acquiring a stereoscopic image of an object includes:
(a) passing image radiation, containing image information relating to the object, through at least a first lens of an optical device;
(b) separating the image radiation into first and second radiation portions, wherein at least one of the following is true: (i) the first and second radiation portions traverse different optical paths and (ii) the first and second radiation portions have one or more differing characteristics;
(c) directing at least a portion of the first radiation portion to an imaging surface of an imaging device connected to the optical device; and
(d) directing at least a portion of the second radiation portion to an ocular of the optical device for viewing by a user. The method can be employed with any of the optical devices described above as well as with a number of other, differently configured optical devices.
Finally, yet another embodiment of the present invention is directed to an infinity or rear-focus conversion lens that is particularly useful with any of the optical devices set forth above. The lens includes:
(a) a macroscopic front lens element that is able to collect light reflected by an object having a larger dimension than the diameter of the macroscopic first lens element; and
(b) a rear lens element that has an at least substantially infinite focal length, whereby the light output by the rear lens element is projected onto a point that is an at least substantially infinite distance from the rear lens element. As used herein, xe2x80x9cmacroscopicxe2x80x9d refers to the reduction of the image acquired to the size of the imaging surface. The macroscopic infinity lens not only permits an optical device using the lens to acquire images having a dimension greater than the infinity lens diameter but also can produce a high quality stereoscopic image due to decreased optical losses. The decreased optical losses or increased optical capture permits the macroscopic infinity lens to capture an image of a higher quality than a conventional microscopic infinity lenses. In one configuration, the optical device can bifurcate the infinity-focused light or signal using prisms, mirrors, polarizers, or signal dividers, such as those described above.
The foregoing summary is neither complete nor exhaustive. As will be appreciated, the foregoing features can be combined or employed in a large number of other devices and/or methodologies. Examples of other devices and/or methodologies that could be modified using one or more of the above features include those described in U.S. patent application Ser. No. 09/354,230, filed Jul. 16, 1999; U.S. Patent Application entitled xe2x80x9cSingle-Lens Stereoscopic Light-Valves and Apparatusesxe2x80x9d, filed Sep. 18, 2000, and having Attorney File No. 4446-6-CIP; and U.S. Provisional Patent Application entitled xe2x80x9cSingle-Lens Stereoscopic Infinity Microscopexe2x80x9d, to Costales, filed on Nov. 3, 2000, all of which are incorporated herein by reference. Such other devices and/or methodologies are considered to be part of the present invention.